U.S. patent number 5,666,243 [Application Number 08/707,121] was granted by the patent office on 1997-09-09 for spring loaded stacked actuator assembly.
This patent grant is currently assigned to Seagate Technology, Inc.. Invention is credited to George I. Brent.
United States Patent |
5,666,243 |
Brent |
September 9, 1997 |
Spring loaded stacked actuator assembly
Abstract
A stacked actuator assembly includes a hub having an axis of
rotation, a first member fixed in a first direction along the axis
of the hub, a second member fixed in a second opposite direction
along the axis of a hub, an actuator arm coupled about the hub
between the first and second members and a spring coupled about the
hub between the first and second members. The spring axially clamps
the plurality of actuator arms between the first and second
members.
Inventors: |
Brent; George I. (Boulder,
CO) |
Assignee: |
Seagate Technology, Inc.
(Scotts Valley, CA)
|
Family
ID: |
24840436 |
Appl.
No.: |
08/707,121 |
Filed: |
September 3, 1996 |
Current U.S.
Class: |
360/265.9;
360/265.7; 360/266.1; G9B/5.187 |
Current CPC
Class: |
G11B
5/5521 (20130101) |
Current International
Class: |
G11B
5/55 (20060101); G11B 005/55 (); G11B 021/08 () |
Field of
Search: |
;360/106,104 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Tupper; Robert S.
Attorney, Agent or Firm: Kinney & Lange, P.A.
Claims
What is claimed is:
1. A stacked actuator assembly comprising:
a hub having an axis of rotation;
a first member fixed in a first direction along the axis of the
hub;
a second member fixed in a second opposite direction along the axis
of the hub;
an actuator arm coupled about the hub between the first and second
members; and
a spring coupled about the hub between the first and second members
to axially clamp the actuator arm between the first and second
members.
2. The actuator assembly of claim 1 wherein the first member
comprises a ring extending about the hub and axially fixed to the
hub.
3. The actuator assembly of claim 2 wherein the first ring
comprises a lip integrally extending from the hub.
4. The actuator assembly of claim 1 wherein the second axially
fixed member comprises a ring extending about the hub and axially
fixed to the hub.
5. The actuator assembly of claim 4 wherein the hub includes an
external groove circumferentially extending about the hub and
wherein the second ring comprises an external snap ring positioned
within the groove.
6. The actuator assembly of claim 1 including a bearing assembly
within the hub.
7. The actuator assembly of claim 1 wherein the spring comprises a
belleville washer.
8. A stacked actuator assembly comprising:
a hub having an axis of rotation;
a first axial stop extending about the hub and fixed along the axis
of the hub;
a second axial stop extending about the hub and fixed along the
axis of the hub;
a plurality of actuator arms coupled about the hub between the
first and second axial stops;
a spacer coupled about the hub between the plurality of actuator
arms; and
a spring coupled about the hub between the first and second axial
stop to axially clamp the plurality of actuator arms between the
first and second axial stops.
9. The actuator assembly of claim 8 wherein the hub includes a
bearing assembly within the hub.
10. The actuator assembly of claim 8 wherein the first axial stop
comprises a lip integrally extending from the hub.
11. The actuator assembly of claim 8 wherein the hub includes an
external groove circumferentially extending about the hub and
wherein the second axial stop comprises an external snap ring
positioned within the groove.
12. The actuator assembly of claim 8 wherein the spring comprises a
belleville washer.
13. A stacked actuator assembly comprising:
an arbor having an outward extending lip at a first end and a
circumferentially extending groove at a second end;
an external snap ring positioned within the external groove of the
arbor;
a plurality of actuator arms coupled about the arbor between the
lip and the external snap ring;
a spacer coupled about the arbor between the plurality of actuator
arms;
a fan tail coupled about the arbor between the lip and the external
snap ring; and
a spring coupled about the arbor between the lip and the external
snap ring to axially clamp the fan tail and the plurality of
actuator arms between the lip and the external snap ring.
Description
BACKGROUND OF THE INVENTION
The present invention relates to disc drive assemblies. In
particular, the present invention relates to a stacked actuator
assembly including a spring for axially clamping the plurality of
actuator arms between first and second axially fixed members.
Disc drives are commonly used with computers to store data on
concentric tracks defined in magnetic codings formed on magnetic
discs. The discs are attached to a rotating spindle which is
powered by a spindle motor. Data is written to and read from
selected tracks on a disc by a read/write transducer head. A
pivotally mounted actuator supports the transducer head and moves
the transducer head across the disc when the head is reading from
or writing to the disc.
Pivotally mounted actuators typically include arms which extend
from a central hub about which the actuator rotates or pivots.
Actuators typically comprise what is known as a unitary E-block
assembly wherein the actuator arms are integrally formed as part of
the hub or a stacked arrangement in which each individual arm is
stacked about a central hub. To prevent slipping of individual arms
or other components in a stacked actuator, nuts or screws are
typically used to fix the arms in proper alignment. However,
rotation of the nuts or screws induces rotational forces which may
cause alignment difficulties during assembly. In addition,
misalignment of the individual actuator arms often results from
thermal shifting after assembly. Misalignment of the actuator arms
causes data reading and writing errors. As a result, there is a
continuing need for a method and apparatus for fixing and reliably
maintaining actuator arms of a stacked actuator in proper
alignment.
SUMMARY OF THE INVENTION
The present invention is a stacked actuator assembly including a
hub having an axis of rotation, a first axial stop about the hub
and fixed along the axis of the hub, a second axial stop extending
about the hub and fixed along the axis of the hub, an actuator arm
coupled about the hub between the first and second axial stops and
a spring coupled about the hub between the first and second axial
stops. The spring applies a pure axial load to the actuator arm
along the axis of the hub to axially clamp the actuator arm between
the first and second axial stops.
In a preferred embodiment of the stacked actuator assembly, a
plurality of actuator arms separated by a spacer are coupled about
the hub between the first and second axial stops. In addition, the
coil assembly is also coupled about the hub between the first and
second axial stops. A spring is coupled about the hub between the
first and second axial stops to axially clamp the plurality of
actuator arms, spacers and the coil assembly between the first and
second axial stops.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top view of a disc drive including an actuator
assembly.
FIG. 2 is an exploded perspective view of a hub assembly, actuator
arms and a fan tail of the actuator assembly.
FIG. 3 is a cross-sectional view of the disc drive of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 is a top view of disc drive 10 with portions removed or not
shown for clarity. Disc drive 10 generally includes housing 12,
spindle motor 14, memory storage discs 16, transducers 18 and
actuator assembly 20. Housing 12 surrounds and encloses spindle
motor 14, memory storage discs 16, transducers 18 and actuator
assembly 20. Spindle motor 14 is conventionally known in the art
and is mounted to housing 12. Spindle motor 14 supports and rotates
memory storage discs 16 for accessing information stored on memory
storage discs 16.
Memory storage discs 16 preferably comprise magnetic discs as are
conventionally used in head disc assemblies. Memory storage discs
16 store data and information. As can be appreciated, disc drive 10
may utilize other types of discs, for example, optical discs, and
other read/write technologies, for example, lasers.
Actuator assembly 20 supports and positions transducers 18 adjacent
to memory storage discs 12 and selectively positions transducers 18
with respect to memory discs 16 for the retrieval and storage of
information from and to discs 16. Actuator assembly 20 includes
actuator arms 24 and voice coil assembly 26. Actuator assembly 20
rotatably supports actuator arms 24 about axis 27 with respect to
memory storage discs 16 and is fixedly coupled to housing 12 by
threaded fastener 28.
Actuator arms 24 are conventionally known in the art. Actuator arms
24 extend over and beneath surfaces of memory storage discs 16 to
support transducers 18 with respect to memory storage discs 16.
Voice coil assembly 26 selectively rotates actuator arms 24 to
selectively position transducers 16 adjacent to memory storage
discs 16 for retrieving and storing information. As conventionally
known, voice coil assembly 26 generally includes pole plates 38,
support posts 40a, 40b, permanent magnets 42 and coil assembly 44.
Pole plates 38 preferably consist of two arcuately curved metal
plates. Pole plates 38 are spaced apart to form a gap and are
mounted to housing 12 by support posts 40a, 40b. Permanent magnets
42 comprise two arcuately curved magnetic members. Permanent
magnets 42 are coupled to an inside surface of pole plates 38
within the gap between pole plates 38. Pole plates 38 and support
posts 40a, 40b provide returns for magnetic fields emanating from
permanent magnets 42.
Coil assembly 44 is conventionally known in the art. Coil assembly
44 consists of a coil 46 of conducting wires wrapped about a center
pole support member 47. Coil 46 and center pole 47 are positioned
between permanent magnets 42. Upon supply of electrical current to
coil 44, under appropriate control as is known in the art, the flux
coupling created between the permanent magnets 42 and coil 46 moves
coil assembly 44 transversely relative to pole plates 38 and
permanent magnets 42. As a result, actuator arms 24, which are
coupled to coil assembly 44, move about axis 27 of actuator
assembly 20 in an arcuate path to position transducers 18 with
respect to memory storage discs 16.
FIG. 2 is an exploded perspective view illustrating actuator
assembly 20 including actuator arms 24 and coil assembly 44 in
greater detail. Actuator arms 24a, 24b, 24c and 24d each include an
annular mounting portion 48 defining an opening 50 extending
through mounting portion 48 and having an inner diameter sized for
being coupled about arbor 60. Similar to actuator arms 24, coil
assembly 44 includes an annular mounting portion 52 defining an
opening 54 extending through mounting portion 52 and having an
inner diameter sized for being coupled about arbor 60.
As shown by FIG. 2, actuator assembly 20 generally includes arbor
60, axial stop 62, spacers 64, 66 and 68, spring 70, bearing
assembly 72 and bearing fastener 74. Arbor 60 is a generally
cylindrical shaped member having a central hub 80 and an outwardly
extending lip 82. Hub 80 is an elongate tube defining axial bore
86, internal lip 87 (shown in FIG. 3), internal groove 88 and
external groove 90. Axial bore 86 extends through hub 80 and is
sized for receiving bearing assembly 72. Internal lip 87 (shown in
FIG. 3) projects from hub 80 partially into axial bore 86 at a
lower end of axial bore 86 opposite to lip 82. As best shown in
FIG. 3, lip 87 acts as a stop for receiving bearing assembly 72.
Internal groove 88 extends into hub 80 about bore 86 and is sized
for receiving fastener 74. Groove 90 circumferentially extends
about hub 70 and is sized for receiving axial stop 62. Hub 80 has
an outer diameter sized for insertion through openings 50 and 54 of
arms 24 and coil assembly 44, respectively, through spacers 64, 66,
68 and through spring 70. Hub 80 preferably has an axial length
sufficient to retain actuator arms 24, spacers 64, 66 and 68 and
spring 70.
Lip 82 integrally extends outward from hub 80 about hub 80. Lip 82
provides a first axial stop for limiting movement of actuator arms
24, spacers 64, 66, 68 and coil assembly 44 along an axis of hub
80. As can be appreciated, various other structures in lieu of lip
82 may be used for providing the first axial stop for limiting
movement of actuator arms 24, spacers 64, 66, 68 and coil assembly
44 along the axis of hub 80. For example, hub 80 may alternatively
additionally include an external groove and an external snap ring
positioned within the external groove to serve as an axial stop in
lieu of lip 82.
Axial stop 62 is positioned opposite lip 82 and provides a second
axial stop for capturing and retaining actuator arms 24, spacer 64,
66, 68, coil assembly 44 and spring 70 about hub 80 of arbor 50.
Axial stop 62 preferably comprises an external snap ring sized for
being receiving within groove 90 of hub 80. Axial stop 62
preferably has a radial width so as to extend outward from the
outer circumferential surface of hub 80. Axial stop 62 limits
movement of actuator arms 24, spacers 64, 66, 68, coil assembly 44
and spring 70 along the axis of hub 80.
Spacers 64, 66, 68 each comprise generally annular shaped rings
having an inner diameter 92 greater than the outer diameter of hub
80, an upper surface 94 and a lower surface 96 for abutting
mounting portions 48 and 52 of actuator arms 24 and coil assembly
44, respectively. Spacers 64, 66, 68 each have an axial length or
thickness for correspondingly spacing apart actuator arms 24a, 24b,
24c and 24d from one another so as to position actuator arms 24a,
24b, 24c and 24d on opposite sides of memory storage discs 16
(shown in FIG. 1). Upon assembly, spacer 64 is coupled about hub 80
between actuator arms 24a and 24b. Spacer 66 is coupled about hub
80 between actuator arms 24b and 24c. Spacer 68 is coupled about
hub 80 between actuator arms 24c and coil assembly 44 and actuator
arm 24d. In lieu of spacer 68, coil assembly 44 may alternatively
be configured for acting as a spacer between actuator arms 24c and
24d. As can further be appreciated, the number of spacers is
dependent upon the number of actuator arms and memory storage discs
employed in the disc drive.
Spring 70 comprises a conventionally known spring captured between
the first axial stop provided by lip 82 and the second axial stop
provided by axial stop 62. Spring 70 applies a pure axial force to
actuator arms 24a, 24b, 24c, 24d, spacers 64, 66, 68 and coil
assembly 44. As a result, spring 70 does not introduce rotational
forces which may cause alignment difficulties during assembly. In
addition, spring 70 prevents slipping of individual arms and other
components in the stacked actuator assembly and prevents
misalignment of actuator arms 24 caused by thermal shifting or
mechanical shock and vibration after assembly. Spring 70 is
preferably a conical or disc spring having an inner diameter 96
greater than the outer diameter of hub 80 to enable spring 70 to
encircle hub 80. At the same time, inner diameter 96 is less than
an outer diameter of axial stop 62 to prevent axial movement of
spring 70 past axial stop 62. Spring 70 preferably has an outer
diameter 98 greater than the inner diameter of mounting portions 48
and 52 of actuator arms 24 and coil assembly 44, respectively.
Spring 70 applies an axial force or load along an axis of hub 80 to
clamp actuator arms 24a, 24b, 24c and 24d between lip 82 of arbor
60 and axial stop 62. Spring 70 preferably comprises a belleville
spring or washer. Alternatively, spring 70 may comprise anyone of a
variety of spring mechanisms such as helical springs, volute
springs, conical springs, slotted washer springs, curved washer
springs, finger washer springs or wave washer springs for applying
an axial force.
Bearing assembly 72 preferably comprises a conventionally known
bearing cartridge sized for being received within axial bore 86. As
conventionally known, bearing assembly 72 is axially secured within
arbor 60 by bearing fastener 74. Bearing fastener 74 preferably
consists of a bowed internal snap ring which is positioned within
internal groove 88 of hub 80 and which engages bearing assembly 72
to retain bearing assembly 72 within bore 86 of arbor 60. Fastener
74 applies an axial force down on the top of bearing assembly 72 to
keep bearing 72 in place with enough force to resist shock. As can
be appreciated, fastener 74 may alternatively consist of any one of
a variety of well-known conventional spring or retainers positioned
within internal groove 88 of hub 80 to retain bearing assembly 72
within bore 86 of arbor 60. As conventionally known, bearing
assembly 72 enables actuator arms 24 and coil assembly 44 to rotate
about the axis of bearing assembly 72 for positioning of actuator
arms 24. Although actuator assembly 20 has been illustrated as
including a distinct bearing assembly 72 retained within arbor 60,
arbor 60 and bearing assembly 72 may alternatively be integrally
formed as a single component.
FIG. 3 is a cross-sectional view of disc drive 10 illustrating
actuator assembly 20. As best shown by FIG. 3, threaded fastener 28
extends through bearing assembly 72 to mount actuator assembly 20
to housing 12. Bearing assembly fastener 74, preferably a bowed
internal snap ring, is received within groove 88 and applies axial
force to the outer housing of bearing assembly 72 and between
bearing assembly 72 to secure bearing assembly 72 within bore 86 of
hub 80. As a result, the outer race or housing of the bearing
assembly 72, arbor 60, actuator arms 24a, 24b, 24c, 24d and coil
assembly 44 rotate about axis 27.
As further shown by FIG. 3, hub 80 extends through openings 50 and
54 of actuator arms 24 and coil assembly 44, respectively to align
actuator arms 24 and coil assembly 44 about hub 80 and about axis
27. In particular, actuator arms 24a, 24b, 24c, 24d, spacers 64,
66, 68 and spring 70 are positioned about hub 80 between lip 82 of
arbor 60 and axial stop 62 in a stacked assembly. Spacer 64 spaces
apart actuator arm 24a from actuator arm 24b. Spacer 66 spaces
apart actuator arm 24b from actuator arm 24c. Spacer 68 spaces
apart actuator arm 24c from coil assembly 44 and from actuator arm
24d. Spring 70 delivers an axial load or force between axial stop
62 and lip 82 to clamp actuator arms 24a, 24b, 24c, 24d, spacers
64, 66, 68 and coil assembly 44 between lip 82 of arbor 50 and
axial stop 62. Spring 70 delivers a pure axial load to actuator
arms 24, spacers 64, 66, 68 and coil assembly 44 to press actuator
arms 24, spacers 64, 66, 68 and coil assembly 44 towards lip 82 of
arbor 60. As a result, spring 70 prevents misalignment of actuator
arms 24 that often results from thermal shifting, mechanical shock
or vibration after assembly. In addition, spring 70 prevents
slipping of individual arms or other components in actuator
assembly 20 to ensure proper alignment without inducing rotational
forces which may cause alignment difficulties during assembly.
Thus, spring 70 fixes and reliably maintains actuator arms 24 of
actuator assembly 20 in proper alignment.
Although the present invention has been described with reference to
preferred embodiments, workers skilled in the art will recognize
that changes may be made in form and detail without departing from
the spirit and scope of the invention.
* * * * *